The invention relates to a method of controlling a speed reduction ratio of a continuously variable speed transmission.
As a measure for controlling the speed of a vehicle equipped with a continuously variable speed transmission by controlling the speed reduction ratio thereof, there has been known a method in which the engine speed is matched with the reference engine speed set in correspondence to the throttle opening of the engine (see, for example, Japanese Patent Laid-Open Publication No. 62(1987)-237164.
In these methods where the engine speed is controlled to match the reference engine speed, the engine output power, and hence the driving power, diminishes, though the engine speed is maintained constant, in a region of low atmospheric pressure such as high altitude regions, and as a result driver feels the driving unenjoyable.